Implement an interface for configuration and metrics

[feed3r]

We should implement some kind REST API to adjust the configuration (write the configuration file) and to show some metrics such as:

• How much data has been transferred
• System status
• other...?

[giorgiozoppi]

Feel free to assign to me. I have some spare time now. Please point out a notion.so group for sharing the design. My idea is to use the simpler: https://github.com/julienschmidt/httprouter
HttpRouter and over there map the api. It's less 'invasive' than gogin.

[feed3r]

It wouldb e really useful if we collect some statistics about the system, such as:

• Status (if it is running, idle...)
• amount of data transferred, this can be done with a counter in the MoveData function (this can be partial, like hourly or total)
• It would be great to measure performance, such as the time spent in moving data
• Don't know if we can also get info about the cpu time...

Then (but in a second moment, too) we can open some REST interface and use some HTTP routing...but for this, I think we can also use the standard library.
Priority is to keep the code as clean and tiny as possible.

We found this very interesting, for example: https://pace.dev/blog/2018/05/09/how-I-write-http-services-after-eight-years.html

[giorgiozoppi]

Here the initial design, please review it:
https://scrawny-newsstand-bd9.notion.site/REST-API-Metrics-fcf6e7f4cb6146e6b6bc9c0afc64fba0
@feed3r @DarioBalinzo